For the better understanding of prior art and the invention reference is made to the fact that all shell surfaces of rotational solids, be they cylindrical, conical or rotational solids of other shapes, have an infinite number of shell lines. The following singled-out linear shell lines M1 and M2 are selected defined positions of the shell lines which lie on a common straight line, are aligned with one another and through which all shell lines traverse successively during the rotation.
U.S. Pat. No. 3,666,049 discloses an expander roller for webs, in which on a stationary arcuate tube a series of cylindrical sleeves axially spaced apart are pivoted by means of roller bearings. These sleeves, in turn, are encompassed by a flexible tubing, which also functions as a seal between the sleeves. Due to the curvature of the arcuate tube, each sleeve has its own rotational axis. As a consequence and relative to fixed reference points of the sleeves, their distances change periodically during the rotation, such that considerable fulling-action occurs within the tubing, which also tends to local displacements on the sleeves with the formation of frictional forces. Since driving the roller takes place through the particular web, considerable tensile stresses occur on it, such that the application—as specified—is limited to high tensile strength webs of textiles, felt and the like. All surface elements of the tubing rotate at the same rotational speed, such that by necessity during the spreading force-consuming circumferential and longitudinal displacements occur of portions of the web on the roller. The document substantially also discusses the lubrication of the bearings by oil mist, which is sprayed into the interspaces between the bearings. However, the individual parts and their assembling are complex and for the purpose of dismantling and maintenance the tubing must be pulled off.
DE 27 25 331 C2 discloses a similar banana-shaped expander roller for webs, which electively can be embodied with or without a jacket of rubber or synthetic material. Each sleeve is only supported at one end by means of a roller bearing on the arcuate tube and with the other is connected with the particular adjacent sleeve via an elastic bushing, such that all sleeves rotate at the same rotational speed and circumferential speed. This document also deals substantially with the lubrication of the bearings by oil mists injected into the interspaces between the bearings. The individual parts and their assembling are, however, complex, and, for the purpose of dismantling and maintenance, the jacket must possibly be pulled off and the sleeves be separated from the elastic bushings.
DE 36 13 494 A1 discloses a similar banana-shaped expander roller for webs, in which, however, the issue concerns the monitoring of the temperature of the roller bearings.
DE 37 33 448 A1 discloses a similar banana-shaped expander roller for webs, in which the issue concerns continuously lubricating the roller bearings of the individual sleeves with grease. Relubricating such rollers is also dealt with in DE 39 19 415 C2.
The principal disadvantages of all “banana rollers” are that the entire surface, be that a tubing or jacket of elastomeric materials, be they cylindrical sleeves in the form of metallic sections of tubes, does not at any site contain or form a straight shell line, and specifically neither on the run-in side nor on the run-out side of the web. Furthermore, the tangential deviation of the jackets or sleeves increases in the direction toward the two ends of the expander roller such that there is the risk of an overstretching the web edges, which cannot be reversed.
EP 0 470 331 B1 discloses inter alia two alternative expander rollers for the simplification of fabrication and assembling, of which the one comprises an arcuate support for outer bushings and the other a straight-line support. In the case of the arcuate support the roller bearings are pivoted directly on such, in the straight-line support by interposing inner bushings with cylinder extensions whose outer faces form an acute angle with the support axis. While at similarly oriented angular position of all inner bushings at two sites a straight-line shell line is generated, viewed transversely to it; however, a sawtooth-form surface profile is generated, with which the web is in intimate contact. In sensitive web material this causes tracks which can no longer be compensated, even through the spreading.
EP 0 527 291 B1 discloses an expander roller with straight-line support, on which several disk-form bushings or rollers with cylindrical circumferential surfaces are disposed. Only the central one of these rollers is precisely perpendicular to the axis of the support, all others are settable hereunto at an acute angle mirror-symmetrically and in groups. However, due to the numerous pivot axes and the associated adjustment mechanisms, the installation and assembling are complex.
DE 199 01 089 A1 according to the species discloses developing an expander arrangement for webs of two truncated cones, whose smallest diameters are oriented toward one another and of which one shell line each is aligned with that of the other truncated cone. When the margins of the web run up onto the thicker ends of the truncated cones, these are stretched, and the web is pulled off from these shell lines in the tangential direction. While such truncated cones have over their entire length the same rotational speed or angular speed, they do not have the same circumferential speed such that, with the exception of its edges, the web is pulled off while being dragged or with slippage from the shell lines of the truncated cones. When pulling off sensitive webs, such as for example thin synthetic material films, these speed differences lead to the formation of scratches, which cannot be eliminated. A further disadvantage is that the ends of the support bodies directed toward one another have a significant distance from one another, i.e. they are not connected with one another, which has a negative effect on the stability of the three-dimensional form and the guidance properties.
EP 0 829 654 A2 discloses arranging in an expander roller to dispose two groups of truncated cone-form rollers on a continuously curved axis. The lesser diameters of the rollers are in the center and their greater diameters—starting from the center—face the outer sides. The production of suitable and reproducible curvatures by bending is extremely difficult. The same applies to the production of basis fitting rollers in accordance with the geometry of the axis. However, unsatisfactory are primarily the fits between the inner bearing rings and the axle. These bearing rings must have a greater diameter than the axle, resulting in the risk of a deviation of the rollers on the axle. All rollers are connected through pins and radial slots, such that, while they rotate with one another and have the same rotational speed, they do however have different circumferential speeds. The result can be that the margin regions of the transported web are displaced faster than the central regions, whereby depending on the frictional factors and the thinness of the guided webs other irregularities can occur during the winding. Due to differing slippage of the web on the expander roller are also generated different driving forces. However, as a rule, an expander roller should be driven by the film, i.e. it should be “towed” with minimum friction.
U.S. Pat. No. 2,925,640 discloses a continuous self-supporting axle only curved angularly in the center, whose straight-line shanks extend from a center piece. On each of these shanks is pivoted a truncated cone-form roller. Between the two truncated cones is disposed a wedge-shaped stationary ring, which is fastened by means of a bracket on a support and whose uppermost shell line is aligned in succession with the adjacent shell lines of the truncated cones. The film or the web must thereby slide over a partial circumference of this stationary ring, whereby again braking effects, scratches and/or path diversions are generated, which are avoided by the invention. Further, through the ring are guided two revolving pins which synchronize the rotational speeds of the two truncated cones. The stationary ring cannot support the axle since the revolving pins do not allow a strut.
The invention therefore has as its aim improving an expander roller arrangement of the above described species to the effect that, in spite of highly simple structuring of the expander roller arrangement, said speed difference is the least feasible when the webs are pulled off, that the development of scratches on the webs does not occur, or is at least negligible, and that the precision of guidance and smoothness of running are improved.
The defined aim is achieved according to the invention in the expander roller arrangement described herein.
Through these constructional measures the defined aim is achieved to its full extent, i.e. said speed difference during the pulling-off of the webs is the least feasible, in spite of the highly simple structuring of the expander roller arrangement, the development of scratches on the webs does not occur, or is at least negligible, and the precision of guidance and smoothness of running are improved. In particular the initial tendency to wrinkle forming, which can be “towed through” a full winding, is successfully counteracted. This is of particular importance in the case of thin webs, for example in the form of synthetic films.
As a rule, the expander roller arrangement precedes at least one treatment or coating station, in particular a coating roller, which transports the web or the webs through the at least one treatment or coating station.
In the course of further formations of the invention it is especially advantageous, if either singly or in combination:                the closed chamber is a vacuum chamber with at least one treatment station for the webs, in particular, if the treatment station is a coating station for the webs,        each group of roller sections is comprised of at least four roller sections,        the supporting bodies are provided with longitudinal bores and radial bores, through which an oil-containing gas can be introduced between two roller bearings each,        the supporting bodies are embodied as hollow cylinders,        the two supporting bodies are connected with one another by a coupling element in the region of the center plane,        the coupling element includes an annular flange with two flat side faces, which form an acute angle with one another and from which project two threaded connection fittings in the direction of the normal, onto which are screwed the supporting bodies,        the coupling element has a throughbore for the connection of the longitudinal bores in the supporting bodies,        the bores in the supporting bodies are connected to a lubricant source, through which a lubricant can be added to the supplied gas,        the surfaces of the groups of roller sections disposed on both sides of the center plane are each located in a common truncated cone surface,        the surfaces of the individual roller sections are comprised of a light metal,        the surfaces of the individual roller sections have a distance of 0.05 to 1 mm on the circumference and in the axial direction,        the axes of the supporting bodies are oriented at an angle of 0.1 to 2 degrees with respect to one another,        the roller bearings are retained at a specified distance through spacer rings and if the roller sections are retained at a distance by inner flanges between the outer rings of two roller bearings, and/or if        the expander roller arrangement is retained between two parallel chamber walls.        
To prevent contaminations within the guide rollers and their bearings, it is proposed that, before aerating the vacuum chamber, a gas is introduced into the interspace or the interspaces, through which solid bodies from the group dust and particles are blown out of the interspace and the penetration of solid bodies into the interspace is prevented.
If the roller bearings include inner and outer rings, it is especially advantageous if the gas is blown through the annular gap between the inner rings and the outer rings, in particular, if the gas during the entire aerating process of the vacuum chamber is supplied through the roller interior.
In the following an embodiment example of the subject matter of the invention, its operational function and advantages will be explained in greater detail in conjunction with FIGS. 1 to 3.